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Flashcards in Leys Exam III Deck (48):

Proteins that have crossed a membrane are

no longer topologically inside the cell. They must recross the membrane to get back inside the cell.


Vesicles move from compartment to compartment within a cell by

budding off and membrane fusion.


Many proteins have signal sequences at their amino terminus that direct the proteins to

cross the membrane. Fewer proteins have internal signal sequences.


The nucleus is surrounded by a

double lipid membrane bilayer, however nuclear pores allow molecules, including proteins to pass from the cytosol into the nucleus and back.


Larger proteins pass through

nuclear pores by an active process


3Nuclear import receptors bind to

nuclear transport signals found on some nuclear bound proteins and facilitate transport into the nucleus.


It generally requires multiple signals to

transport proteins from the cytosol into the luman of the mitochondria.


There are multiple protein

translocators in the mitochondrial membrane. Each translocator interacts with a specific set of proteins.


Transport of protein into the mitochondria requires



Proteins enter peroxisomes using a mechanism similar to

mitochondrial entry


Proteins travel from the endoplasmic reticulum (ER), through the

golgi to many sites


A signal recognition protein (SRP) binds to the

signal sequence during translation and directs the nascent peptide to the ER membrane.


Proteins bound for the mitochondria are translated in the

cytosol and than transported through the mitochondrial membrane. A process that requires ATP.


Proteins that are headed into or through the ER are transported through the

ER membrane during translation. This process does not require any additional energy.


Carbohydrate modification of proteins in the

ER helps direct them to their ultimate location


The “default pathway” if there are no other signals directing the protein to other locations, is to

send the protein to the cell surface


In regulated secretory pathway cells store proteins in secretory vesicles until they are

signaled to release them from the cell by fusion of the vesicles with the cellular membrane


signaled to release them from the cell by fusion of the vesicles with the cellular membrane

appetite, energy expenditure, genotype, digestion, metabolism, availability of food, customs and presence of disease.


Leptin, Ghrelin and Insulin are

important regulators of food intake.


Leptin circulates, in the body, at levels proportional to

body fat


Leptin signals the brain that the body has

had enough to eat, or satiety


Adipose tissue produces adipokines that regulate

metabolic processes to meet the body’s needs


AMP and AMP/ATP regulate

AMP-activated kinase (AMPK) that senses cellular energy levels


AMPK regulates

rate-limiting enzymes in energy-producing and using pathways.


High levels of AMPK activity inhibit

energy-utilizing pathways and stimulate energy generating pathways.


Increased Ghrelin increases



Ghrelin favors accumulation of

lipids in the visceral fatty tissue


Estimated average requirements (EAR) for calories changes with

age and sex. Estimated daily protein requirements vary with age and sex.


The ideal amount of calorie intake in a day is

equal to the calorie utilization for that day.


Recommended daily allowance (RDA) for a nutrient is a value that is

adequate for the great majority of individuals. The estimated average requirement (EAR) reflects amount that is adequate for half of the population.


Different nutrients have different

energy content. Fat has the highest energy content per weight. Alcohol has a high-energy content


Increases in obesity are correlated with an increase in

the use of high fructose corn syrup.


High fructose corn syrup is made by

breaking down cornstarch into glucose using amylase followed by conversion to fructose with glucose isomerase.


There are several potential health issues associated with comsumption of high fructose corn syrup including

mercury exposure, hypertension, elevated cholesterol, long-term liver damage, increased risk of diabetes and weight gain and obesity.


Protein-calorie malnutrition causes a number of health problems including:

decreased protein synthesis and glucose transport, fatty liver, liver necrosis and fibrosis, depression, hypothermia, compromised immune function and would healing, decreased cardiac and renal function, loss of muscle.


Obesity is associated with an increased risk for several conditions including

type 2 diabetes, hypertension and stroke, dyslipidemia, gall stones, respiratory disorders, musculoskeletal disorders and several cancers including breast, endometrial, ovarian, gall bladder and colon.


Trans fatty acids are

not essential and provide no benefit to human health.


Saturated fats increase levels of

LDL cholesterol (bad cholesterol


Trans fats increase levels of

LDL and also lower levels of HDL (good cholesterol); thus increasing the risk of coronary heart disease


1. Drug metabolism can take place anywhere in the body (Plasma, kidney, lung, gut wall) but

liver is the prime site


1. There are three potential outcomes of drug metabolism:

1. 1)Increase in drug hydrophilicity and ability to be excreted (hepatic) 2)Metabolic products are less pharmacologically active than the substrate drug 3)Inactive prodrugs converted to their active forms (hepatic


1. There are several mechanisms of Drug Resistance including:

1) decreased permeability 2) alteration of the target site for the drug 3) enzymatic inactivation of the drug 4) active transport of the drug out of the cell 5) amplification of the gene coding for the target of the drug.


An increase in DNA repair activity can

decrease effectiveness of drugs that target DNA.


1. Multidrug resistant results from an

1. increase in the amount of transporter proteins that can pump many different drugs out of the cell.


Cell proliferation

the process that results in an increase of the number of cells, and is defined by the balance between cell divisions and cell loss through cell death or differentiation. Cell proliferation is increased in tumours


Cell specialization, 3) Cell interaction



the 4 essential processes needed to develop from a single cell into a multicellular organism

1) Cell proliferation, 2) Cell specialization, 3) Cell interaction, 4) Cell movement.


cell movement

a complex phenomenon primarily driven by the actin network beneath the cell membrane, and can be divided into three general components: protrusion of the leading edge of the cell, adhesion of the leading edge and deadhesion at the cell body and rear, and cytoskeletal contraction to pull the cell